Abstract Watson-Crick L systems are string generating formal models obtained by augmenting Lindenmayer with the morphism inspired complementarity principle. The is controlled a trigger —a boolean condition eventually met generated word. Despite their simplicity, (D)0 have interesting mathematical properties, strong generative power, and they can also characterize some open decision problems. Fu...

Changes in the structural and solvation dynamics of a 15mer AT DNA duplex upon melting of the double-helix are observed by a combination of ultrafast two-dimensional infrared (2D-IR) and optical Kerr-effect (OKE) spectroscopies. 2D-IR spectroscopy of the vibrational modes of the DNA bases reveal signature off-diagonal peaks arising from coupling and energy transfer across Watson-Crick paired ba...

Vascular entry is a decisive step for the initiation of long-distance movement of infectious and endogenous RNAs, silencing signals and developmental/defense signals in plants. However, the mechanisms remain poorly understood. We used Potato spindle tuber viroid (PSTVd) as a model to investigate the direct role of the RNA itself in vascular entry. We report here the identification of an RNA mot...

An ab initio method is used in a two state model to calculate consistent relative enthalpies and free energies for the stacking of nucleic acid bases in deoxyribose dinucleotides and the Watson-Crick hydrogen bonding interactions between mononucleotides when uncharged and singly charged. Favorable free energy changes are determined for the formation of dimers between mononucleotides by Watson-C...

http://www.exploratorium.edu/origins/coldspring/ideas/printit.html[9/24/2010 6:13:14 AM] Figure 1 This figure is purely diagrammatic (8). The two ribbons symbolize the two phophate-sugar chains, and the horizonal rods the pairs of bases holding the chains together. The vertical line marks the fibre axis. Print this page If the link above doesn't work, try typing Ctrl + P on a PC or Apple + P on...

The model we consider are stateless counter machines which mix the features of one-head counter machines and special two-head Watson-Crick automata (WK-automata). These biologically motivated machines have reading heads that read the input starting from the two extremes. The reading process is finished when the heads meet. The machine is realtime or non-realtime depending on whether the heads a...